The present invention refers to a closure on a cartridge, particularly intended for a double cartridge. Generally, dispensing cartridges are sealed at the dispensing end with some kind of closure or stopper which is removed when the cartridge is to be used. In order to dispense a substance by means of a dispensing appliance, an attachment is generally secured to the cartridge, the attachment being a static mixer in the case of double cartridges. The cartridge outlet is often sealed by a membrane or a foil which must be pierced in some way for use. Although objects of some kind for piercing the membrane may be present at the site where such cartridges or dispensing appliances are used, the objects nevertheless have to be previously provided. Moreover, if the cartridge is not completely emptied after its use, or if it is to be used again, there is a risk that the substance spills out of the pierced opening(s) of the cartridge and causes contaminations which may result in olfactory or skin irritations.